You could carry a Bugrom plushie or something around with you (particularly if you have one of the little messenger Bugrom that appeared a few times). I mean, that way; the people that recognize it will know you're Jinnai, and the people that don't wouldn't know who you were anyway.Besides a "prop" like that, though... I don't know. You could prominently carry a comb in your front pocket (helpful if you can get your hair to look like his), and that might help, but honestly; there's so many white guys in business suits (not so many that are blue, but still) in anime that you're really out of luck. *chuckles*
You might also consider wearing badges like the ones Jinnai eventually wears in the OAVs. The "Bugrom Big Raid Medal of Victory", among others.
Possibly that goofy bug suit he was wearing in the second OVA, though I'd know nothing of how to make costumes.
As long as you have the laugh down pat, it should be a cinch.